In molding operations using metal molds, especially in the case of molding operation for many different small-lot products, the core change type dies are normally used for the efficiency of die changing operation. These type of dies comprise a stationary die and a movable die. The stationary die consists of a stationary mother mold and a stationary cope detachably coupled with the stationary mother mold, whereas the movable die consists of a movable mother mold and a movable cope detachably coupled with the movable mother mold. These stationary and movable dies ape paired when used in the molding operation. These stationary die and movable die cooperate with each other fop a common function.
Conventionally, the core change has been be changed by manual operation. For facilitating such manual die changing operation, however, in many instances, so-called rectangular cassette type copes, which allow an operator to insert or eject the core in a direction normal to the closing direction of the dies, have been used. Beside these rectangular cassette type cores, there are rounded cassette type cores which allow an operator to insert or eject the core into a mother mold in the same direction as the closing direction of the dies. These rounded cassette type cores are advantageous due to their compactness in size and lightness in weight, but are disadvantageous due to a lack in adequate hold for the operator, in extracting them.
The rectangular cassette type cores are too heavy to handle with a robot, and so the rounded cassette type cores, being compact and light, will be preferable for automation of the molding operation, although they are as equally difficult to handle, as in the case of manual handling. This is true especially when a parting surface of the mother mold and a parting surface of the core are substantially flush with each other, and, in such a case, it is almost impossible to extract the core from the mother mold by the robot hand. To overcome this problem, it can be considered to provide a means for pushing the core from behind. Such a means, however, is not applicable to a part such as the stationary die of the molding machine where a sprue bushing or the like is located, because it is difficult to push a core by means of a mechanism at a stationary side, although applicable to a part such as the movable die of the molding machine which structurally permits the installation of an ejector or spring.